Concious sedation is one conventional method of managing young, uncooperative children who have dental restorative needs. There are no well-controlled clinical studies which have systemically investigated the relationships between the variables of psychosedative agents, patient behavior, and multiple physiologic parameters during restorative procedures in pediatric dentistry. The propse of this study is to determine the effects of chloral hydrate (CH) on children's clinical behavior, heart rate (HR), blood pressure (BP), respiratory rate (RR), peripheral oxygen saturation (02), expired carbon dioxide (C02), frontalis electromyographic (EMG) and electroencephalographic (EEG) activity during routine restorative treatment. Three dosages of CH and a placebo will be studied. (CH) dosages will be 25, 50 and 75 mg/kg body weight. CH and the placebo will be administered per oris. The subjects of this pilot study will be 24 young (18-36 months of age), uncooperative children who are healthy, but present with caries in a minimum of four of the six quadrants (anterior and posterior). Four appointment periods will be necessary to complete their individualized treatment. The three dosage levels and placebo per group will vary in a Latin square design with each subject receiving three levels of CH and the placebo across four appointments. Fifteen patients will be assigned to each group constituting the four sequences of drug dosages and placebo in the Latin square design. The behavioral and physiologic responses of the child will be rated and recorded during five general phases (pre-opreative, topical anesthesia, injection of local anesthesia, rubber dam application and cavity preparation) respectively. The child will continue to be monitored post-operatively for 30 minutes or until they can be released to parental care. The operator and rater of the behavior will be "blinded" to drug and placebo. All children will have their teeth restored according to the usual and customary standard care at the clinic. ANOVA and Pearson Product Moment Correlation Coefficient will be used to determine: a) any significant dosage effect of CH and placebo on the physiologic parameters at each recording phase and b) any significant correlation among physiologic parameters, respectively. Chi square analysis will be used to evaluate behavioral response categories per dosage level of CH and placebo in each recorded phase.